Electronic medical systems such as, for example, cardiac pacemakers, defibrillators or neurological devices such as, for example, brain pacemakers for deep brain stimulation, spinal cord stimulation devices, TENS (Transcutaneous Electrical Nerve Stimulators) or devices for muscular stimulation therapy, and diagnostic devices analyzing the chemical properties of the patient's blood, other body parts or other body properties and parameters, frequently employ electrode leads, which are run in the patient's body and remain there at least for the period of the treatment or measurement. The electrode leads are connected in an electrically conductive manner to the optionally implantable electronic system.
These medical systems typically comprise a housing, which may be biocompatible, having an associated electronic circuit and an energy supply, such as, for example, a battery. The housing comprises at least one connection point to which the electrode lead or the electrode leads can be connected. The electrode lead or the electrode leads are used for transmitting the electric energy from the housing to the body part to be treated or analyzed, and vice versa.
To this end, the term “electrode lead” in medical technology denotes not only an element which is used to transmit electric energy according to the physical definition, but also comprises a lead having an electric conductor, together with the enveloping insulation thereof, which frequently is designed as an insulating tube, and all further functional elements which are rigidly connected to the lead. The electrode lead, for example, also comprises what is referred to as the electrode tip, by way of which the electric energy is introduced into the tissue to be treated. Frequently, an electrode tip is also provided with anchoring elements or retaining structures, which are used to ensure that the spatial position of the transition point of the electric energy in the tissue to be treated remains constant. The electrode tip, which forms a transition point of the electric energy into the tissue, can be designed as a recording, stimulating or working electrode.
In such electrode leads, an insulating hose made of silicone is frequently used to insulate the electrically conductive elements outside of the connection and electrode tip. Silicones have a high biocompatibility, sufficient hardness, and excellent permanently elastic properties.
For example, if an electrode lead chafes the collarbone of a person or a second electrode lead (for example, when a plurality of electrode leads are implanted), it is possible that the insulating tube is abraded so far that the functionality of the electrode lead is impaired.
For this reason, searches have been conducted for ways to increase the abrasion resistance of an insulating tube.
The published prior art DE 10 2008 010 188 A1, for example, proposed an insulation tube, wherein on the lateral surface of an inner, hollow-cylindrical layer a second layer is disposed, which comprises at least one polymer from the group consisting of polyurethane and silicone-polyurethane copolymer. The long-term stability of polyurethane, however, is not sufficient for many application purposes because the material degrades over time. In principle, degradation of the material also cannot be excluded for the therein proposed two-layer solution. In addition, such an electrode lead is considerably harder than a single-layer electrode lead having silicone insulation because of the arrangement of two layers on top of each other. This effect is particularly relevant for thin electrode leads. Furthermore, the concept of using an insulation tube made of two coaxially disposed layers is quite complex from a manufacturing engineering point of view.
Further, already known solutions relate to the development of new materials which combine the properties of silicone and polyurethane, such as the copolymers PurSil (silicone polyether urethane), CarboSil (polycarbonate urethane) or Elast-Eon®. These materials are so new that no long-term experience data is available yet. The use of these materials for medical applications is therefore also accordingly complex because of the extensive tests that are required.
The present invention is directed at overcoming one or more of the above-identified problems.